Clutches are well known devices used to selectively connect a source of rotational power, such as the crankshaft of an internal combustion engine and its flywheel, to a driven mechanism, such as a transmission. Typically, clutches have a driven disc rotatably fixed to the transmission input shaft and axially disposed between a flywheel and a pressure plate. Both the flywheel and the pressure plate are rotatably fixed to the output shaft of the engine. The pressure plate is axially biased toward the flywheel by an axial spring load. When the clutch is in an engaged condition, the pressure plate clamps the driven disc against the flywheel. Friction material is disposed on the driven disc to resist slipping between the driven disc and both the pressure plate and the flywheel. When the clutch is in a released condition, the axial spring load is overcome by a release mechanism, unclamping the driven disc. With the driven disc unclamped, relative rotation between the transmission input shaft and the engine output shaft becomes possible. When the clutch is reengaged, the pressure plate is pressed against the friction material, halting relative rotation between the engine output shaft and the transmission input shaft.
The driven disc is annularly divided into two relatively rotatable portions: the hub which is rotatively fixed to the input shaft, and the annular disc assembly which bears the friction material. The damping springs are disposed between the hub and the annular disc assembly.
The annular disc assembly has a relatively stiff portion, called a reinforcing plate, which engages the damper springs. A thinner annular disc extends outwardly radially from the reinforcing plate and bears the friction material. Using thinner material for the annular disc than the reinforcing plate allows the assembly to be of sufficient strength to engage the damper springs while being of relatively low rotative inertia. Commonly, the annular disc is riveted to the reinforcing plate. It is desired to provide a connection between the annular disc and the reinforcing plate which is stronger than the connection provided by rivets. It is also desired to provide a connection between the reinforcing plate and the annular disc which is well suited for adapting to specific packaging and space constraint limitations within a clutch assembly.